A thermally heated body can lose the absorbed energy of its activated orbitals in very small increments to a wide range of electron orbital energy differentials; the frequency vs. intensity plot produces the Boltzman distribution seen in black body radiation.

Max Planck’s interpretation of the Boltzman black body radiation experiment provided the foundation for the concept of quantum mechanics. The black body radiation plot of Intensity vs. Frequency shows a progression of low intensity at low frequencies, peak intensity in the center frequencies, and low intensity at high frequencies. Planck hypothesized the black body emitted only discreet frequencies, with each frequency separated by tiny increments. The frequencies emitted are related to Planck’s constant, which is an extremely small unit of angular momentum. This small difference in angular momentum separates each frequency. This discreet frequency emission gave the first evidence of the quantum nature of energy emission/absorption. In other words, photons cannot assume every arbitrary energy level. Rather, photons can only carry packets of energy corresponding to integer multiples of Planck’s constant (h).